Machine for grinding lenses.



PATENTED MAY 31, 1904.

F. M. CLARK. v MACHINE FOR GRINDING LENSES.

APPLICATION FILED FEB. 17, 1904.

2 SHEETBBHEET 1.

iwo MODEL.

W/E/JTU PCLWJLM maria I No. 761,207. 'PATBNTED'MAY a1, 1904,

I P. M. (IL-ARK.

MACHINE FOR GRINDING LENSES.

APPLIOA'TION rum) I'm-.17, 1904. no MODEL. 2 snnnTs-snnn'r 2;

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in the claims.

UNITED STATES rammed May 31, 1904.

PATENT 2 OFFICE.

FRANK M. CLARK, OF TILTON, NEW HAMPSHIRE.

SMACHINE FOR GRINDING LENSES.

SPECIFICATION forming part of Letters Patent No. 761,207, dated. May 31,1904.

v Application filed February 17, 1904. Serial No. 194,092. (No model.)

Be it known that I, FRANK M. CLARK, a citizen of the United States,residing at Tilton, in

the county of Belknap and State of New Hampshire, have invented new anduseful Improvements' in Machines for Grinding Lenses, of which thefollowing is a specification;

This invention relates to a machine for grinding lenses and in theadaptation of my invention hereinafter described, and set fort-h lens,saidconvex surface having a different radius of curvature longitudinallyfrom the radius of curvature upon which it is formed laterally thereof.

The object of the invention is to providea simple and easily-operatedmachine which will i automatically adjust itself to grind with'ac-;

curacy and nicety lenses of different radii of curvature. I Theinvention consists, 1n a machine of the character described, of acarrier, a holder for a lens pivotally supported upon said carrier, astatlonary grinder, means to press said lens against said grinder, andmechanism pivotally connected to said carrier whereby said holder.

is moved in a curvilinear path over the surface of said grinder, themedian pivotal line of saidholder extending transversely of andintersecting a portion of said grinding-surface. a i

The invention, again, consists in the combination and arrangement ofparts set forth in the following specification, and particularly pointedout in the claims thereof.

Referring to the drawings, Figure 1 is a side elevation of my improvedmachine for grind.

ing lenses. Fig. 2 is a section, partly in elevation, taken on line 2 2of Fig. 1 looking toward the left in said figure. Fig. 3 is asection,=partly in elevation, taken on line 3 3 of Fig. 2; Fig. 4 is adetail plan of the carrier as viewed inthe direction of the arrow a,Fig.

1; Fig. 5 is a front elevation in detail of the lens-holder viewed inthe direction of the ,arrow 6, Fig. 1.,-

Like numerals refer,to like parts throughout the several views ofthedrawings.

' In the drawings, 10 is the frame of my im- The machine is particularlyadapted to grind a convex surface upon a toricproved'lens-grindingmachine, which may be ofany suitable construction and shape. 11 is astationary grinder, preferably constructed of castiron, supported uponsetscrews 12 12, having screw-threaded engagement with braces 13 13,fast to the frame 10. The grinder 11 has a concave inner surface 14corresponding to the convex form which it is desired to impart to thelens to be ground. In the particular form of grinder illustrated in thedrawings the longitudinal curve 15 of the concave surface 14 isdescribed from the center 16 of a stay-rod 17 by means of which the twosides of the frame 10'are fastened together. Said side frames 10 arefurther stiffened and fastened together by the braces 13. Theconcaveinner surface 14 is formed upon a shorter curve 18 at right angles tothe longitudinal curve 15, as seen in Fig. 2, said curve 18 beingdescribed from the center 19, this being the configuration of theinterior surface of the grinder 11, and in order to impart the desiredform to the lens to be ground it will be seen that the mechanism bywhich the lens is passed over said surface 14 during the grindingoperation, as hereinafter described, must yield and conform itself tothe different positions of said lens, so that the lens -as it is pressedagainst and moved around over said concave surface 14 in a series ofcurves will not be tipped up upon its edges, but will be subjected to aconstant and even pressure.

The lens 20 is fastened to a plate 21, which is maintained in a fixedrelation to a holder 22 by pins 23,fast to said holder and projectinginto said plate. The holder 22 is shown in detail in Fig. Sand consistsof a central portion 24 and two curved side arms 25 25. Said side armsare pivoted at 26 26 to a carrier 27.

'It will be noted that the median pivotal line passing through thecenter of the pivots 26 intersects the portion of said grinding-surfacemeans of a ball-joint 28 to the rocker-arm 29, ,said rocker-arm beingpivoted upon the stayrod 17. The rocker-arm 29 is prevented from movinglongitudinally upon said stay-rod by collars 30 30, fast to saidstay-rod, and consists as a whole of a casting 31, provided with arecess 32, into which a rod 33 projects, said rod being provided with aspherical end to [it in a corresponding recess formed in the car rier 27and adjustably fastened to the casting 31 by a set-screw 34, so that thedistance from the center of the ball-joint to the center of the rod 17may be varied to suit different radii of curvature for differentlenses.The lower end of the carrier 27 is provided with a crank-pin 35,fastthereto, which projects into a suitablyshaped hole 36 formed in acrank-arm 37, fast to a shaft 38, journaled to rotate in asleeve 39,constituting abearing therefor. The sleeve 39 is provided with a groovedflange 40, constituting apulley, and is journaled to rotate in a bracket41, fast to the base 42. It will be noted that the median center linesof the shaft 38 and of the bearing 39 converge, so that said shaft iseccentrically journaled in the pulley 40. The lower end of said shaft 38has a pulley 43 fast thereto. Both of the pulleys 40 and 43 arepreferably driven by round leather belts; The carrier 27 has the upperend thereof extended, forming an arm 44, which is connected by a spring45 to a stationary pointas, for instance, in this case the stay-rod 17.It will be noted that the action of thespring 45 is to press the lensagainst the concave inner surface 14 of the grinder 11 with a yieldingpressure by'tipping the carrier 27 upon the ball-joint 28. It will benoted that a line passing through the center of the ball-joint 28 andintersecting the median line of the pivots 26 when prolonged downwardlywill intersect the median line of the crank-pin 35 midway between theupper and lower sides of the crank-arm 37. The carrier 27, with itscrank-pin 35, constitutes, in efiect, a link, one of the pivots of whichis located above the grinder 11viz., on the ball-joint 28and the otherbelow said grinder in the crank-arm 37. In Fig. 1 broken lines y, g andy indicate, respectively, the two extreme positions and the centralposition of the rocker-arm 29, and the broken lines z, .2 and .2indicate, respectively, the two extreme positions and the centralposition of theholder 22, as indicated by a plane extending through themedian center of the pivots 26 and of the center 16 about which the are15 is described. When the rocker-arm 29 is in its central position, aline a: a; drawn at right anglesto the line 2 should intersect the liney at the center of the balljoint 28.

The general operation of the mechanism hereinbefore described is asfollows: The lens having been attached to the plate 21 by means of tarand resin, the lens is moved about in a series of curves over theconcave surface 14 of the grinder 11. Water and emery in the properproportions are poured into the grinder 11 from time to time, and thepulleys 43 and 40 are rotated by belts, as herei'nbefore described, thepulley 43 being rotated,

preferably, about eight times to one rotation of the pulley 40. Theresult of the combined rotation of the pulleys 43 and 40 is that the 26and through the center of the ball-joint 28,

and hence there is no tendency of the holder 22 to tip the lens overupon its edges during the operation of grinding said lens, hereinbeforedescribed.

It will be seen that if the curve 18 is described with a shorter radiusthan that indicated in the drawings the center 19 would necessarilybe'lowered from the position shown in the drawings, and this wouldchange the relative position of the center of the balljoint to thecarrier 27. To adapt the machine to lenses of different radii, the ball28 fits into a hemispherical recess formed in 'a'block 46, which isfastened to the arm 44 by a'screw 47. Holes 48 are provided at differentpoints upon the arm 44, Fig. 3, at the proper location, so

that the rocker-arm 29 may be set for different-curv'ed lenses, thelocation of the holes 48 being governed by the rule for determining thecentral position of the ball-joint 28 hereinbefore set forth.

While I have described the median center line of the pivots 26 asintersecting a line connecting thepivotal points of the link-carrier 27,said median center line may be moved slightlysay onesixteenth of aninch--above or below said line without interfering materially with theoperation of the machine or detracting from the quality of the workproduced thereby, and'I therefore do not wish to limit my invention to amachine constructed with the connecting-line drawn between the pivotalpoints of said carrier-link exactly intersecting the median center lineof the pivots whereby the lens-holder is pivoted to said carrier.

Having thus described my invention, what I claim, and desire to secureby Letters Patent, 1s

1. In a machine for grinding lenses, a rockerarm, a rotary crank, acarrier, constituting a link, one end thereof pivoted to said rockerarmthe other to said crank, a holder for a lens pivoted to said carrier,and a stationary grinder against which the surface of said lens isadapted to be pressed.

2. In a machine'for grinding lenses, a rockerarm, a rotary crank, acarrier, constituting a link, one end thereof pivoted to said rockerarmthe otherito said crank, a holder for a lens pivoted to said carrier, astationary grinder against which the surface of said lens is adapted tobe pressed, and means to press said lens against said grinder. I

3. A machine for grinding lenses comprising in its construction acarrier, a holder for a lens pivotally supported upon said carrier,

a stationary grinder, means to press said lens anism constructed toimpart a curvilinear motion to one end of said carrier, whereby saidlens is carried in a curvilinear path over the surface of said grinder.

5. A machine for grinding lenses comprising in its constructionarocker-arm, a carrier pivoted thereto, a grinder, a holder for a lenspivoted to said carrier, and means to press said lens against thesurface of said grinder in combination with a crank connected to saidcarrier, a shaft fast to said crank, and a rotary sleeve in which saidshaft is eccentrically journaled. 1 V

6. A machine for grinding lenses comprising in its constructionarocker-arm, a carrier pivoted thereto, a grinder, a holder for a lenspivoted to said carrier, and means to press said lens against thesurface of Said grinder; in combination with a crank connected to saidcarrier, a shaft fast to said crank, a pulley in which said shaft iseccentrically journaled, and independent mechanisms to rotate saidpulley and shaft.

7. A machine for grinding lenses comprising in its construction arocker-arm, a carrier pivoted thereto, a grinder, a holder for a lenssaid lens against the surface of said grinder; in combination with acrank connected to said carrier, a shaft fast to said crank, a rotarysleeve in which said shaft is eccentrically journaled, and mechanism torotate said shaft and sleeve at different rates of speed.

8. A machine for grinding lenses comprising in its construction agrinder having a curved grinding-surface, a pivotally-supported carrier,a holder for a lens pivoted to said carrier and adapted to hold saidlens against said curved grinding-surface, the median pivotal line ofsaid holder extending transversely of and intersecting a portion of saidgrindingsurface.

9. A machine for grinding lenses comprising in its construction agrinder having a curved grinding-surface, a carrier constituting a link,one of the pivots of said link located above, the other below, saidgrindingsurface, and a holder for the lens pivoted to said carrier andadapted to hold said lens against said grinding-surface, the medianpivotal line of said holder extending transversely of and intersecting aportion of said grindingsurface.

10. A machine for grinding lenses comprising in its construction agrinder having a curved grinding-surface, a carrier constituting a link,one of the pivots of said link located above, the other below, saidgrindingsurface, and a holder for the lens pivoted to said carrier andadapted to hold said lens against said grinding-surface, the medianpivotal line of said holder substantially intersecting a line connectingthe pivotal centers of said link-carrier.

In testimony whereof I. have hereunto set my hand in presence of twosubscribing witnesses.

FRANK M. CLARK. Witnesses:

CHARLES S. Goonnve, ANNIE J. DAILEY.

pivoted to said carrier, and means to press

